1. Field of the Invention
The present invention relates to a wireless communication system and a method thereof, and, more particularly, to a wireless communication system and a method thereof in wireless infrastructure networking environments.
2. Description of the Related Art
Recently, wireless networking environments, together with wireless communication technology developments, have become widespread in everyday life. For example, as an alternative technology for a conventional wired LAN, Wireless Local Area Network (WLAN) technologies such as IEEE 802.11 are being used more and more. The IEEE stands for the Institute of Electrical and Electronics Engineers.
The IEEE 802.11 wireless LAN features the use of a wireless Radio Frequency (RF) technology using the 2.4 GHz band called the “Industrial Scientific Medical(ISM) band,” instead of the use of cable, thereby enabling the networking capability to be equal to that of the wired LAN. There are two transmission modes of infrastructure networking and Ad-hoc networking for the IEEE 802.11 wireless LAN. Here, the Ad-hoc mode, in which a network is constructed with only devices mounting a wireless LAN therein, is not connected to external networks. That is, communications are performed among the wireless LAN devices in the Ad-hoc mode, so that the Ad-hoc mode is used for small-sized offices or small-scaled networks.
The infrastructure mode can be used in offices with environments that are equal to that of the existing wired LAN, and wireless networks for the infrastructure mode are constructed with access points, which are wired/wireless interfacing devices, connected to wired networks (Ethernets). An access point serves as a bridge between a wireless LAN device and a wired LAN device, enabling mutual data transmissions and receptions.
A wireless device has to exist in a wireless communication range of an access point to communicate with wired devices through the access point, and has the same ID as a basic service set identifier (BSSID) and a service set identifier (SSID) assigned to the access point. To do so, the wireless device receives a beacon frame that an access point periodically sends when a wireless LAN channel is changed. The wireless device, having received the beacon frame, sends a response message for an association request to the access point sending the beacon frame.
The access point, having received the association request from the wireless device, sends an association response message to the corresponding wireless device, including a BSSID and an SSID assigned to the access point. The wireless device receives and registers the association response message for its own network information, so that a communication channel is linked between the access point and the wireless device.
If a communication channel is linked between an access point and a wireless device, the wireless device can form one network with wired devices through the access point, and share the network resources. However, if the access point does not perform normal operations due to system defects such as a system failure, wireless devices connected to the access point cannot participate in the network any more. In this case, the wireless devices connected to the access point temporarily stop their data transmission/reception operations, and wait for an arbitrarily set period of time. Thereafter, the wireless devices attempt to associate with the access point, but cannot connect to the corresponding network until the access point performs its normal operations. Accordingly, there exists a problem in that the communication efficiency between the wireless devices and the access point is reduced.